A Review of the Implementation of the USEPA Quality-Corrective Direction Performance Approach into Molecular Isotope-Dilution Mass Spectrometry Assays.

The U.S. Environmental Protection Agency's (EPA) Performance-Based Measurement System (PBMS), now known as the Performance Approach, is approaching its 30th anniversary. This critical review examines its origins, goals, and the obstacles that have hindered its implementation, while assessing the progress made to date and its status. By addressing key questions and providing specific illustrations, this review offers insights into reinvigorating the initiative, with an emphasis on regulating flexibility and fostering a culture of accountability. Furthermore, this analysis informs the testing community and data users of how outdated mental models continue to negatively influence stakeholders during the generation and application of isotope-dilution mass spectrometry (ID-MS) analytical data. The proposed solutions call for a shift in attitude, encouraging practitioners and users to responsibly prioritize specific results and data fitness-for-purpose over the strict adherence to dictated procedures.